KOSPI jumps 3.7% as Anthropic IPO filing revives chip stocks

Key takeaways

• South Korea's benchmark KOSPI was up 3.71% at 5,672.64 at 00:05 UTC (09:05 KST) on Tuesday, October 27, according to Yahoo Finance data, a day after it fell 1.46% to close at 5,469.47.
• Yonhap reported the index opened 189.18 points, or 3.46%, higher at 5,658.65, and credited renewed AI optimism after Anthropic's US IPO filing and softer oil prices.
• Chipmakers led early trade: Etoday reported Samsung Electronics up 3.52% and SK hynix up 4.86% at 09:03 KST, with foreign investors net buyers of 409.8 billion won.
• The cause is attributed by local media and one brokerage analyst; no Korea-specific policy or company announcement has been reported as a trigger.

What happened: why the KOSPI jumps on Tuesday

The KOSPI jumped more than 3.7% in the first minutes of Tuesday trading in Seoul, recovering all of Monday's loss as AI and semiconductor stocks rallied after Anthropic filed for a Nasdaq listing and oil prices eased overnight, according to Yonhap and Etoday.

The index opened at 5,658.65 at 09:00 KST (00:00 UTC), up 3.46% from Monday's close, Yonhap reported. By 09:03 KST it had reached 5,666.67, up 3.61%, according to Korea Exchange figures cited by Etoday. Yahoo Finance showed the index at 5,672.64, up 3.71%, at 00:05 UTC. The tech-heavy KOSDAQ opened 2.18% higher at 743.09 and was up 2.59% at 746.06 at 09:03 KST, Etoday reported.

The move followed a positive session on Wall Street. According to Seoul Economic Daily, the Nasdaq Composite rose 0.83% to 26,169.38 on Monday, the S&P 500 gained 0.70% to 7,676.77, the Dow added 0.28%, and the Philadelphia Semiconductor Index climbed 2.82%. Money Today reported overnight gains of 2.4% for Nvidia, 3% for Micron and 2.8% for AMD.

What we know

• AI sentiment. Yonhap said investor sentiment improved after Anthropic disclosed strong revenue growth in its US IPO filing, which revived interest in AI-related shares ahead of big tech earnings and the Federal Reserve's rate decision. Seoul Economic Daily, citing the filing, reported first-half 2026 revenue of $16.29 billion. Money Today reported that Anthropic plans to list on Nasdaq in mid-November under the ticker "ANT". Bullquill's earlier report covers the Anthropic S-1 filing and ANT listing.
• Oil and the Middle East. Yonhap linked the oil decline to hopes of easing Middle East tensions after reports of Qatari mediation involving Iran and the United States. Seoul Economic Daily reported that senior officials from Saudi Arabia, Pakistan and Turkey visited Tehran and met President Masoud Pezeshkian, while a tanker fire off the UAE coast limited the drop in crude.
• Analyst view. Han Ji-young of Kiwoom Securities, quoted by Etoday, tied the rally to Anthropic's filing lifting US AI and chip sentiment and to Middle East talks that slowed the rise in WTI prices.
• Who bought. At 09:03 KST, foreign investors were net buyers of 409.8 billion won on the KOSPI, while individuals were net sellers of 462.1 billion won and institutions sold 10.1 billion won, Etoday reported.
• Chip and holding stocks. By 09:09 KST, Money Today reported SK hynix up 6.51%, Samsung Electronics up 4.69%, Samsung Electro-Mechanics up 6.8% and SK Square up about 10.5% at 850,000 won.

What we don't know yet

• Whether the gain holds through the session. Early-morning moves after a sharp gap higher can fade; the closing level has not been published.
• No Korean government, Bank of Korea or company announcement has been reported as a trigger. The explanations above come from news reports and one analyst, not from an official statement.
• How much of the move reflects positioning ahead of earnings. SK hynix is due to report third-quarter results on Wednesday, October 28, and Samsung Electronics on Thursday, October 29, according to Seoul Economic Daily and Yonhap.

Background

Seoul stocks have swung widely in October. The KOSPI dropped about 3% on October 23 as chip stocks followed a US sell-off, and fell again on Monday as Brent crude hovered near six-month highs and reports of possible renewed strikes on Iran weighed on risk appetite. Samsung Electronics and SK hynix make up a large share of the index, so sentiment toward AI memory demand tends to drive its biggest daily moves. The South Korea stocks weekly brief sets out the earlier drivers.

What it means

Tuesday's opening shows how closely the KOSPI is tied to two outside forces right now: US enthusiasm for AI, which feeds directly into demand expectations for Korean memory chips, and oil prices, which matter for an energy-importing economy. Both moved in the market's favour overnight. The next tests come quickly, with SK hynix and Samsung earnings on October 28 and 29 and the Fed decision this week. Any return of Middle East tension, or a weak read on AI spending, could reverse part of the move, as happened earlier this month.

This article is for information only and is not investment advice.